JP2003260960A - Automatic engine stopping and restart device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such the problem that when the holding of the braking force of each wheel is released simultaneously after the completion of automatic engine restart after idling stop, uncomfortable squeezing is given to the driver on a downward slope or the equivalent. <P>SOLUTION: When an automatic engine restart command is output (S1) and the drive force of an engine can be transmitted to the wheels (S2), with the inlet valve of an ABS actuator closed, Hill holder control is performed to hold the brake force of the wheels (S3). When automatic engine restart is completed (S4), with the inlet valve corresponding to a pair of the rear wheels opened, the holding of the brake force is released (S6), and after the elapse of a specified time ΔT1 (S7), the inlet valve corresponding to a pair of the front wheels opened, the holding of the brake force is released (S8). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic engine stop and automatic restart of a vehicle for automatically stopping and restarting the engine under predetermined conditions when the vehicle is temporarily stopped at an intersection or the like. Regarding the device.

[0002]

2. Description of the Related Art In recent years, the engine is automatically stopped during a temporary stop of the vehicle such as waiting for a signal while the vehicle is running, so-called idle stop, and the engine is automatically restarted at the time of starting from such a signal waiting. An automatic engine stop / restart device for starting has been proposed. In such a device, when the automatic restart of the engine is performed in a state where the driving force of the engine can be transmitted to the drive wheels, as in the case where the shift position of the automatic transmission is the drive position such as the D range, There is a risk that the driver may feel uncomfortable due to the torque fluctuations from the stop state (no-load state) of the engine to the complete explosion.

As a countermeasure against this, Japanese Patent Laid-Open No. 2000-1279
Japanese Patent Publication No. 27 discloses a technique of braking the vehicle when the engine is automatically restarted by changing the shift position of the automatic transmission to the drive position. Further, when the braking force is reduced after the automatic restart, if the braking force is suddenly reduced, for example, in the case of a downhill, the driver may have a feeling of pushing the vehicle forward. The publication describes that the braking force is gradually (continuously and steplessly) reduced.

[0004]

However, if the braking force is actually changed steplessly, the size of the device is greatly increased and the cost is increased. For example, by closing a hydraulic pressure holding solenoid valve provided on the upstream side of a hydraulic circuit of a well-known ABS (anti-lock brake system) actuator that prevents wheel lock, during automatic restart of the engine. In the case of a configuration that holds the braking force, in order to gradually reduce this braking force,
It is necessary to provide an orifice passage in parallel with the solenoid valve or to adjust the opening amount of the solenoid valve in a stepless manner, which leads to an increase in size of the apparatus and an increase in cost. The present invention is
This is done in view of such problems.

[0005]

The automatic engine stop / automatic restart device for a vehicle according to the present invention automatically stops and restarts the engine in accordance with the operating state of the vehicle. This device holds a brake applying means for applying a braking force to each of a plurality of wheels, and the above braking force when the engine is automatically restarted in a state where the driving force of the engine can be transmitted to the driving wheels. It has a holding means and a releasing means for releasing the holding of the braking force by the holding means after the engine is automatically restarted. Then, when releasing the holding of the braking force by the releasing means, the braking force releasing timing of at least two pairs of wheels is set so that the total braking force corresponding to the sum of the braking forces of the plurality of wheels gradually decreases. Different from each other.

The present invention is preferably implemented using a well-known ABS actuator. That is, the brake force is retained by closing the inlet valve of the ABS actuator, the retention of the brake force is released by opening the inlet valve, and the brake force is released by making the opening timings of the plurality of inlet valves different from each other. Different times.

[0007]

According to the present invention, when releasing the holding of the braking force after the completion of the automatic restart of the engine, the total braking force corresponding to the sum of the braking forces of the plurality of wheels gradually decreases. In addition, since the braking force release timings of at least two pairs of wheels are different from each other, as in the case of continuously reducing the braking force described above, a drastic reduction of the braking force can be prevented while preventing a drastic decrease of the braking force. It is possible to achieve simple simplification and cost reduction.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a system configuration of a vehicle equipped with an automatic engine stop / restart device common to first and second embodiments described later. For example, an engine 1 including a gasoline engine is configured to drive front wheels, which are driving wheels, via an automatic transmission 2, and includes an injector 3 for injecting and supplying fuel, an ignition plug (not shown), and the like. There is. A starter motor 4 is provided so as to crank the engine 1 via a ring gear (not shown).

As sensors for detecting the operating state of the vehicle, a throttle sensor 5 for detecting the opening of a throttle valve of the engine 1, an engine speed sensor 6 for detecting the engine speed, and a brake pedal 7a ( (See FIG. 2), a brake pedal switch 7 for detecting the depressed state, a shift switch 8 for detecting the shift position of the automatic transmission 2, and a total of four wheel speed sensors 11 for detecting the rotational speeds of the front, rear, left and right wheels. A brake fluid pressure sensor 12 that detects a brake fluid pressure of a master cylinder 21 (see FIG. 2) of a known brake device (brake applying means) that applies a braking force to each of a plurality of wheels is provided. These detection signals are used to automatically stop the engine 1.
It is input to the vehicle controller 10 that controls the entire vehicle including automatic restart.

The ignition key switch 9 is generally provided in the vicinity of the driver's seat and has an OFF position, an accessory position that enables operation of audio and lighting, and an ignition position equivalent to turning on the main switch of the vehicle. , And a start position for performing cranking by the starter motor 4. The vehicle controller 10 starts the control when the key is inserted into the keyhole and the accessory position is passed to the ignition position, and the power is always turned on regardless of the position of the ignition key switch 9.

The ABS (Anti-Lock Brake System) has an actuator 20 that operates in response to a signal sent from the vehicle controller 10, and a wheel speed sensor 11 is provided to prevent wheel lock (slip). The braking force of the corresponding wheel is adjusted based on the rotation speed of the wheel detected by.

FIG. 2 shows a hydraulic circuit of the ABS actuator 20. This ABS has a wheel speed sensor 11 and a control system for each wheel, and is of a four-sensor, four-channel, four-wheel independent control type capable of independently controlling the braking force of each wheel. However, any ABS having a control system of two or more channels can be applied to the present invention. In FIG. 2, FR, FL, RR, and RL are added to the components corresponding to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel after the reference symbols, respectively.

In the main brake passage 23, which connects the master cylinder 21 of the brake device and a total of four wheel cylinders 22 provided for each wheel, the wheel cylinder 2 is provided.
A total of four inlet valves 27 are provided according to the number 2. A pump 25 that is driven by a motor 24 and pressurizes is connected to the main brake passage 23. A first check valve 26 that prevents the reverse flow of the brake fluid is provided in the pressurizing passage that connects the pump 25 and the main brake passage 23. In the return passage 28 for returning the brake fluid from the wheel cylinder 22 to the pump 25, a total of four outlet valves 29 are provided according to the wheel cylinder 22, and a reservoir 30 for temporarily storing the brake fluid and a reverse flow of the brake fluid are provided. Second to prevent
A check valve 31 is provided.

The inlet valve 27 and the outlet valve 29 are two-position switching type solenoid valves for increasing, holding and reducing the hydraulic pressure of the wheel cylinder 22 in accordance with a signal sent from the vehicle controller 10.
During normal braking (when ABS is not operating), neither the inlet valve 27 nor the outlet valve 29 is energized, and the inlet valve 27 is open and the outlet valve 29 is closed. Therefore, the hydraulic pressure of the master cylinder 21 is directly transmitted to the wheel cylinder 22 through the main brake passage 23, and the brake fluid does not flow to the reservoir 30. When the braking force is maintained by the ABS control, both the inlet valve 27 and the outlet valve 29 are closed to maintain the brake pressure in the main brake passage 23. During depressurization by ABS control, the inlet valve 27 is closed and the outlet valve 29 is opened. As a result, the brake fluid in the main brake passage 23 passes through the return passage 28, and a part thereof is stored in the reservoir 30.
And is returned to the pump 25. ABS
When the pressure is increased by the control, the inlet valve 27 is opened, the outlet valve 29 is closed, and the pump 25 is driven to increase the pressure, as in normal braking.

FIG. 3 shows changes in the brake fluid pressure (a) and the engine speed (b) during automatic engine stop and automatic restart. It should be noted that the characteristics shown in FIG. 3 do not hold and gradually release the braking force as in the embodiment described later, and even before and after automatic restart,
The brake fluid pressure gradually decreases according to the amount of depression of the brake pedal.

For example, when the vehicle speed is 0 and the brake pedal is depressed, it is regarded as a temporary stop at an intersection or the like, and the engine is automatically stopped, that is, idle stop is performed. The conditions for this idle stop are:
In addition to the vehicle speed being 0 and the brake pedal being depressed, there is sufficient remaining battery charge (S.O.C.), and the brake fluid pressure is the predetermined first threshold value. P1 or more is included. Also, when the vehicle is started from the automatic stop state of the engine,
Automatically restart the engine. Specifically, a starter switch (not shown) is turned on to operate the starter motor 4 to crank the engine 1. This automatic restart start command is output, for example, when the depression of the brake pedal is released and the brake fluid pressure drops to a predetermined second threshold value P2 lower than the first threshold value P1. This second threshold value P2 allows the vehicle to be stably braked and pushed out to the driver even when the vehicle is temporarily stopped on a downhill, regardless of the torque fluctuation caused by the automatic restart of the engine. It is set to a value that does not give a sense of discomfort. The automatic stop and automatic restart of these engines are executed by another routine not shown.

FIG. 4 is a flow chart showing a characteristic brake control flow when the engine is automatically restarted according to the first embodiment of the present invention. This control processing is performed by the vehicle controller 1.
Executed by 0. FIG. 5 is a timing chart showing changes in the brake fluid pressure at the time of automatic restart according to the first embodiment. The solid line (a) in FIG. 5 shows the average of the brake fluid pressures of all the wheel cylinders, and corresponds to the total braking force, which is the sum of the braking forces of all the wheels. The broken line (b) shows the hydraulic pressure of the master cylinder, and the hydraulic pressure of this master cylinder corresponds to the depression amount of the brake pedal.

In S (step) 1, it is determined whether or not a command to start the automatic restart of the engine is output. When S1 is affirmed, the routine proceeds to S2, where it is determined whether the driving force of the engine 1 can be transmitted to the driving wheels. In particular,
It is determined whether the shift switch 8 of the automatic transmission 2 is in the drive position, that is, the D range or the first speed or second speed range. S
When 2 is affirmed, the routine proceeds to S3, and at the same time when the automatic restart of the engine is started, the hill hold (brake force holding) control using the ABS actuator 20 is started (holding means). More specifically, since the brake pedal is being depressed during the automatic stop of the engine, the inlet valve 27 is the same as during the normal braking described above.
Is open and the outlet valve 29 is closed. In the hill hold described above, the outlet valve 29 is kept closed and the inlet valve 27 is also closed to keep the brake fluid pressure of the wheel cylinder 22 regardless of the depression amount of the brake pedal. At the start of this hill hold, the four inlet valves 27 are closed at the same time, and the braking forces of all the wheels are held simultaneously.

At S4, it is determined whether the automatic restart of the engine is completed. For example, the engine speed detected by the engine speed sensor 6 is monitored, and when a predetermined time elapses after the engine speed exceeds a predetermined threshold value corresponding to the idle speed, the engine has completely exploded. Therefore, the determination in S4 is affirmative. If the determination in S4 is affirmative, the process proceeds to S5, and a hill hold cancellation command is output. The hill hold is released by switching the inlet valves 27 from closed to open, but if the four inlet valves 27 are simultaneously switched to open, the total braking force of the vehicle corresponding to the sum of the braking forces of all the wheels is increased. Because it drops sharply, for example, when you are stopped on a downhill,
This may give the driver a feeling of extrusion. Therefore, in this embodiment, the timing at which the inlet valve 27 is switched from the closed state to the open state, that is, the braking force release timing is made different between the pair of front wheels and the pair of rear wheels. That is, at the first time T1 immediately after the complete explosion of the engine, the two inlet valves 27RR, 27RL corresponding to the pair of rear wheels that are the driven wheels.
Is switched from closed to open (S6). This first time T1
Is determined using a well-known timer or the like (S7), and at a second time T2 after the lapse of the predetermined time ΔT1, the two inlet valves 27FR, 27FL corresponding to the front wheels that are the drive wheels are set. Switch from closed to open (S
8). The processes of S5 to S8 correspond to the releasing means of the present invention.

The above-mentioned elapsed time ΔT1 is a fixed value of about 20 to 100 ms which is preset according to the engine rotation speed and engine torque increase characteristics after the complete explosion. However, ΔT1 may be variably controlled according to the operating condition of the engine. The first time T1 may be almost the same as the complete explosion of the engine, or may be delayed by a predetermined amount from the complete explosion. The holding hydraulic pressure P2 ′ of the wheel cylinder at the time of hill hold is the same value as the second threshold value P2, or the second threshold value when the first timing T1 is delayed from the complete explosion. The value is slightly lower than P2. When the brake fluid pressure detected by the brake fluid pressure sensor 12 drops to a predetermined holding fluid pressure P2 ', S3
The hill hold control may be started.

As described above, in this embodiment, when the holding of the braking force of the wheels is released after the completion of the automatic restart of the engine, the total braking force corresponding to the sum of the braking forces of the plurality of wheels is gradually reduced. As described above, since the braking force release timings of the front wheels and the rear wheels are different from each other, it is possible to prevent the sudden reduction of the braking force as in the case of continuously reducing the braking force described above. It is possible to greatly simplify and reduce the cost. Especially AB
By switching the inlet valve 27 of the S-actuator 20, it is possible to maintain and gradually release the braking force during automatic restart. In the case of a vehicle equipped with ABS, most mechanical parts can be added or changed. Its application is extremely easy because it does not need to be added.

Further, only when the driving force of the engine can be transmitted to the driving wheels, specifically, when the shift switch 8 of the automatic transmission is in the driving position of the D range or the first speed or the second speed range. , S2 to S3, the hill hold control is performed, and when the driving force of the engine is not transmitted to the driving wheels, specifically, when the shift switch 8 is in the non-driving position N range or P range, the determination of S2 is made. Is denied, the hill hold control is prohibited and unnecessary braking is prevented.

Referring to FIG. 2, in a typical ABS actuator, an inlet passage is provided in inlet valve 27, and only the flow of brake fluid from wheel cylinder 22 to master cylinder 21 is allowed in parallel with inlet valve 27. There is a return check valve that enables the inlet valve 27 when the brake is normally released.
Bypass the orifice passage of the wheel cylinder 2
The second brake fluid is promptly returned to the master cylinder 21. On the other hand, in the ABS actuator 20 according to the present invention as shown in FIG. 2, the return check valve and the orifice passage are omitted because it is necessary to reliably hold the hydraulic pressure of the wheel cylinder 22 during the hill hold. However, there is no practical problem.

FIG. 6 is a timing chart showing how the brake fluid pressure changes during automatic restart according to the second embodiment of the present invention, and corresponds to FIG. 5 in the first embodiment. In the second embodiment, the braking force release timings of all four wheels are made different from each other. Specifically, the left rear wheel inlet valve 27RL is opened at the first timing U1 corresponding to immediately after the completion of the automatic restart, and the second valve after the first predetermined time ΔU1 has elapsed from the first timing U1. At the time U2, the right rear wheel inlet valve 27RR is opened, and at the third time U3 after the second predetermined time ΔU2 has elapsed from the second time U2, the right front wheel inlet valve 27FR is opened,
At the fourth timing U4 after the lapse of the third predetermined time ΔU3 from the third timing U3, the inlet valve 27FL for the left front wheel is
To open. In this way, by making all the braking force release timings of the four wheels different, it is possible to obtain the same effect as that of the first embodiment, and also to reduce the total braking force of the entire vehicle more smoothly. Can be

The present invention is not limited to the above-described embodiments, but includes various modifications and changes without departing from the spirit of the present invention. For example, the above first and second
In the embodiment, first, the holding of the wheel braking force on the rear wheel side, which is the driven wheel, is released, and then the holding of the braking force on the front wheel side, which is the driving wheel, is released. However, the present invention is not limited to this. It is also possible to release the holding of the braking force on the front wheel side, which is, and then release the holding of the braking force on the rear wheel side, which is the driven wheel.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a vehicle equipped with an engine automatic stop / automatic restart device according to the present invention.

FIG. 2 is a configuration diagram showing a hydraulic circuit of an ABS actuator according to the present invention.

FIG. 3 is a timing chart showing a threshold value of a brake fluid pressure for automatically stopping and restarting the engine.

FIG. 4 is a flowchart showing a flow of brake control according to the first embodiment of the present invention.

FIG. 5 is a timing chart showing changes in brake fluid pressure according to the first embodiment.

FIG. 6 is a timing chart showing changes in brake fluid pressure according to the second embodiment of the present invention.

[Explanation of symbols]

1 ... engine 12 ... Brake fluid pressure sensor 20 ... ABS actuator 27 ... Inlet valve

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 29/02 321 F02D 29/02 321A F term (reference) 3D041 AA01 AA66 AB01 AC01 AC26 AC30 AD02 AD04 AD31 AD41 AD44 AD51 AE02 AE41 AE43 3D046 BB03 BB28 CC02 DD04 EE01 FF05 GG02 HH02 HH05 HH07 HH16 HH17 HH36 LL02 LL05 LL17 LL21 3G092 EA08 EA17 FA30 GA04 GA10 HA06ZA11 DB23 CA11 DB23 CA21 DB23 CA11 DB23A11

Claims (4)

[Claims] 1. An automatic engine stop / automatic restart device for a vehicle that automatically stops and restarts the engine according to the operating state of the vehicle, and a brake applying means for applying a braking force to each of a plurality of wheels, When automatic restart of the engine is performed in a state where the driving force of the engine can be transmitted to the driving wheels, a holding means for holding the braking force and a holding means for holding the braking force by the holding means after the automatic restart of the engine are performed. And a releasing means for releasing the braking force of at least two pairs of wheels so that the total braking force corresponding to the sum of the braking forces of the plurality of wheels is gradually reduced. An automatic engine stop / restart device for vehicles, which is different from each other. 2. The holding means closes a plurality of ABS actuator inlet valves respectively provided for the wheel sets, and the opening means makes the opening timings of the inlet valves different from each other. Item 1. An automatic engine stop / auto restart device for a vehicle according to item 1. 3. The automatic engine stop / automatic restart device for a vehicle according to claim 1, wherein the releasing means changes the braking force releasing timings of a total of four wheels in the front, rear, left and right directions. 4. A brake fluid pressure detecting means for detecting a brake fluid pressure is provided, and the engine is automatically stopped when the vehicle is stopped and the brake fluid pressure is equal to or higher than a first threshold value. The automatic engine stop of the vehicle according to any one of claims 1 to 3, wherein when the brake fluid pressure drops to a second threshold value lower than the first threshold value, automatic restart of the engine is started. Automatic restart device.